const int THERMISTOR_PIN = 0;
const float referenceResistance = 10000.0; // Resistance at reference temperature (in ohms)
const float referenceTemperature = 25.0; // Reference temperature in degrees Celsius
const float beta = 3950; // Beta value of the thermistor
int i = 0;
int sinceStart = 0;
float averageArray[600];
bool calculateData = false;
int entryCount = 0;
unsigned long shortTime;
float minValue = 1000;
float maxValue = 0;

void setup() {
  Serial.begin(115200);
  delay(100);
  Serial.println("STARTING PROGRAM...");
  Serial.println("========================================");
  Serial.println("ATTENTION: Enter '1' for Average Value");
  Serial.println("      Made by:  Brendon Hauck");
  Serial.println("              (6/2/23)        ");
  Serial.println("      ESP32 Temperature Reader");
  Serial.println("========================================");
  pinMode(THERMISTOR_PIN, INPUT);
}

void loop() {
  if (Serial.available()  > 0) { //checks to see if there is any input into the Serial Port
    char average = Serial.read();
    if (average == '1') { // if that value is true, begin to take the average
      calculateData = true;
    }
  }
  if (i >= 600) { //Checks if i has passed 600, meaning 10 minutes of data have passed
    i = 0;
  }
      
  int rawValue = analogRead(THERMISTOR_PIN);
  float voltage = rawValue * (3.3 / 4095); // Convert ADC value to voltage
  float resistance = ((3.3 * referenceResistance) / voltage) - referenceResistance; // Calculate thermistor resistance
  float steinhart = 1.0 / ((resistance / referenceResistance) / beta + 1.0 / (referenceTemperature + 273.15)); // Steinhart-Hart equation
  float temperatureC = steinhart - 273.15; // Temperature in Celsius
  float temperatureF = (temperatureC * 9.0 / 5.0) + 32.0; // Temperature in Fahrenheit
  if (millis() > (shortTime + 1000)) {
    Serial.print(sinceStart);
    Serial.print(" Seconds: ");
    Serial.print(temperatureF); //End of Conversion Data
    Serial.println("ºF");
    averageArray[i] = temperatureF; //sets the current temperature into an array slot, starting at 0, increasing up to 599, for 10 minutes worth of data
if (calculateData) { //Begin to average the numbers
      entryCount++; // Increment the number of entries
      float average;
      if (entryCount < 600) {
        average = calculateArrayAverage(averageArray, entryCount); // Calculate the average value using the available entries
      } else {
        average = calculateArrayAverage(averageArray, 600); // Calculate the average value using the latest 600 entries
      }
      if(minValue >= temperatureF){
        minValue = temperatureF;
      }
      if(maxValue <= temperatureF){
        maxValue = temperatureF;
      }
      Serial.println("===============");
      Serial.println("DATA RECORD");
      Serial.print("Average: ");
      Serial.print(average);
      Serial.println("ºF");
      Serial.print("Min Temp: ");
      Serial.print(minValue);
      Serial.println("ºF");
      Serial.print("Max Temp: ");
      Serial.print(maxValue);
      Serial.println("ºF");
      Serial.println("===============");
      calculateData = false; // Reset the flag
    }

    i++;
    sinceStart++;
    shortTime = millis();
  }
}

float calculateArrayAverage(float arr[], int length) {
  float sum = 0;
  for (int j = 0; j < length; j++) {
    sum += arr[j];
  }
  return sum / length;
}